ABSTRACT/PROJECT SUMMARY Lung cancer is the leading cause of cancer-related mortality for both men and women in the United States. The number of new cases of lung cancer exceeds 220,000 yearly; with an appalling five year survival of 16% for non-small-cell lung cancer (NSCLC). The overall goal of the proposed research is to decrease suffering and improve survival for NSCLCs harboring epidermal growth factor receptor (EGFR, ErbB1) or ERBB2 mutations (i.e., >20% of all NSCLCs; the most common cause of cancer death worldwide). EGFR mutated NSCLCs comprise diseases with a distinct biology marked predominantly by targetable mutations involving inframe indels in exon 19 and the point mutation L858R. Some tyrosine kinase inhibitors (TKIs) can effectively inhibit signaling from these aberrant kinases, disrupt their downstream signaling cascades and induce apoptosis. TKIs are now clinically available (gefitinib, erlotinib, afatinib and osimertinib) or in development as palliative therapies for advanced EGFR mutated NSCLC. However, the third most prevalent group of EGFR mutations in NSCLC (>10% of cases) is composed of inframe insertions (of 1-4 amino-acids spanning residues E762 to C775) within exon 20 of EGFR that are insensitive to approved EGFR TKIs. Therefore, the identification of therapies that can or not abrogate kinase activity for EGFR exon 20 insertion mutated NSCLCs are essential to understand the promises plus limitations of precisions therapies for this cohort of tumors. The close homology of EGFR and ErbB2 insertion mutations highlights that future therapeutic options for EGFR exon 20 insertion mutations will be applicable to other cohorts of NSCLC. The proposal will take advantage of our budding comprehensive models to completely characterize EGFR exon 20 mutants and identify novel therapies for this genomic subgroup of tumors. Aim 1 will establish robust preclinical models to represent EGFR exon 20 insertion mutations as a homogenous group; with a goal of generating novel models that are necessary to evaluate therapies against these NSCLCs. Aim 2 will evaluate available and novel therapies against EGFR exon 20 mutants; with a goal of identifying effective therapies - including EGFR/ERBB2 exon 20 mutant specific TKIs ? and their putative mechanisms of resistance. Aim 3 will support the clinical development of an EGFR/ERBB2 exon 20 mutant specific TKI; with a goal of confirming the clinical efficacy of such a class of drugs and designing rational combination therapies to prevent the development of acquired resistance. The final translational goals of these models are to provide rational concepts that can be explored initially in confirmatory clinical trials and subsequently in the clinical care of patients. If these goals are met, quality of life and survival of patients will be extended beyond what is currently available.